Early recurrence of febrile seizures during acute illness: risk factors and lack of association with long-term epilepsy in a Pediatric cohort

Background Febrile seizures (FSs) are a common neurological manifestation in children, affecting 2%–5% of children worldwide. While acute-phase recurrences during the same febrile illness are frequent, their risk factors and implications for long-term epilepsy remain incompletely understood. This study aimed to identify independent risk factors for recurrent FSs (RFS) during the acute febrile phase and clarify their association with long-term epilepsy development. Materials and methods This retrospective cohort study included 611 children (aged 6 months to 3 years) diagnosed with FSs at a tertiary pediatric hospital in Shanghai between April 2021 and March 2023. Clinical data on seizure recurrence patterns, demographic characteristics, and influenza A infection status were collected. Multivariate logistic regression was used to identify independent risk factors for acute-phase RFS. Long-term outcomes, including subsequent seizure recurrence and epilepsy incidence, were compared between children with and without RFS using Kaplan–Meier survival analysis, with differences assessed by the log-rank test. Results The median time to recurrence was 6 h after the initial seizure, and 94.95% of recurrent events occurred within 24 h. Independent risk factors for acute-phase RFS were a prior history of FSs [odds ratio (OR) = 2.24, 95% confidence interval (CI): 1.42–3.56] and positive influenza A infection (OR = 3.34, 95% CI:1.96–5.71). Among 99 children with RFS, 22.22% experienced further seizures and 2.02% developed epilepsy during a median follow-up of 39 months (interquartile range: 37–41). In the non-recurrent FS group ( n = 512), 19.14% had later seizures and 0.39% developed epilepsy. Although any subsequent seizure (febrile or afebrile) was more frequent in the RFS group, the difference in long-term seizure risk was not statistically significant [log-rank χ 2 = 0.74, p = 0.391; hazard ratio (HR) = 1.223, 95% CI: 0.770–1.942]. Conclusion Acute-phase FSs recurrence is common and typically occurs within 24 h, with prior FSs history and influenza A infection as key risk factors. However, early recurrence was not associated with increased long-term epilepsy risk. These findings support close monitoring of high-risk children during febrile illnesses while alleviating unnecessary concerns regarding future neurologic outcomes.